The field of the invention is in solid state memory devices and more particularly in nonvolatile random access memory devices.
Static volatile RAM memory cells are well known. Nonvolatile memory cells have recently been disclosed. Typical prior art devices are exemplified by U.S. Pat. No. 3,881,180 to patentee Gosney; U.S. Pat. No. 3,877,055 to patentees Fisher and Powell; U.S. Pat. No. 3,845,327 to patentee Cricchi; and U.S. Pat. No. 3,683,335 to patentees Cricchi and Beydler. The concept of virtually nonvolatile data storage also was presented by J. C. Lockwood et al at the 1972 WESCON, Sept. 19-22, 1972, Los Angeles, CA.
The novelty of the present invention resides primarily in the combination comprising variable threshold load devices in a static RAM cell and the method of operation of MNOS transistors in an n-channel circuit.